U.S. patent application number 13/671386 was filed with the patent office on 2013-12-12 for structure of an electrochemical separation membrane and manufacturing method for fabricating the same.
This patent application is currently assigned to ENERAGE INC.. The applicant listed for this patent is ENERAGE INC.. Invention is credited to Yuan-Hsin Chang, Jing-Ru Chen, Cheng-Yu Hsieh, Shu-Ling Hsieh, Mark Y. Wu.
Application Number | 20130327702 13/671386 |
Document ID | / |
Family ID | 49714428 |
Filed Date | 2013-12-12 |
United States Patent
Application |
20130327702 |
Kind Code |
A1 |
Wu; Mark Y. ; et
al. |
December 12, 2013 |
STRUCTURE OF AN ELECTROCHEMICAL SEPARATION MEMBRANE AND
MANUFACTURING METHOD FOR FABRICATING THE SAME
Abstract
A structure of an electrochemical separation membrane and a
manufacturing method for fabricating the same are disclosed. The
structure of an electrochemical separation membrane includes a
base-phased polymer part in form of a continuous phase structure, a
fabric-supported part distributed in the base-phased polymer part
in striped shape to provide mechanic strength thereto, and
inorganic particles distributed uniformly in the base-phased
polymer part with 0.1 wt %.about.50 wt %, wherein the
fabric-supported part is a porous structure with a plurality of
micro holes such that the base-phased polymer part filled into the
micro holes to obtain better adhesive strength, inorganic particles
distributed uniformly in the base-phased polymer part to reduce the
shrinking of separation membrane and hence improving the thermal
stability under high temperature. A lithium ion battery applying
the electrochemical separation membrane of the present invention
can reduce resistance, increase charge/discharge capacitance and
prolong lifespan.
Inventors: |
Wu; Mark Y.; (Yilan County,
TW) ; Hsieh; Cheng-Yu; (Yilan County, TW) ;
Chang; Yuan-Hsin; (Yilan County, TW) ; Chen;
Jing-Ru; (Yilan County, TW) ; Hsieh; Shu-Ling;
(Yilan County, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ENERAGE INC. |
Yilan County |
|
TW |
|
|
Assignee: |
ENERAGE INC.
Yilan County
TW
|
Family ID: |
49714428 |
Appl. No.: |
13/671386 |
Filed: |
November 7, 2012 |
Current U.S.
Class: |
210/499 ;
427/385.5 |
Current CPC
Class: |
H01M 2/1666 20130101;
H01M 2/1646 20130101; B01D 71/48 20130101; B01D 71/34 20130101;
H01M 2/1653 20130101; B01D 71/54 20130101; B01D 71/56 20130101;
H01M 2/1686 20130101; B01D 71/64 20130101; Y02E 60/10 20130101;
B01D 71/024 20130101; B01D 2325/40 20130101; B01D 69/10 20130101;
B01D 67/0002 20130101; B01D 71/42 20130101; B01D 67/0079 20130101;
B01D 69/148 20130101 |
Class at
Publication: |
210/499 ;
427/385.5 |
International
Class: |
B01D 69/10 20060101
B01D069/10; B01D 71/34 20060101 B01D071/34; B01D 71/42 20060101
B01D071/42; B01D 71/02 20060101 B01D071/02; B01D 71/56 20060101
B01D071/56; B01D 71/64 20060101 B01D071/64; B01D 71/48 20060101
B01D071/48; B01D 67/00 20060101 B01D067/00; B01D 71/54 20060101
B01D071/54 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 11, 2012 |
TW |
101120929 |
Claims
1. A structure of an electrochemical separation membrane,
comprising: a base-phased polymer part in form of a continuous
phase structure; a fabric-supported part distributed in the
base-phased polymer part in striped shape in order to provide
mechanic strength thereto; and inorganic particles distributed
uniformly in the base-phased polymer part with 0.1 wt %.about.50 wt
%, wherein the fabric-supported part is a porous structure with a
plurality of micro holes such that the base-phased polymer part is
filled into the micro holes.
2. The structure of the electrochemical separation membrane
according to claim 1, wherein the base-phased polymer part is
selected from the group consisting of at least one of
polyvinylidene fluoride, polyethylene terephthalate, polyurethane,
polyethylene oxide, polypropylene oxide, polyacrylonitrile,
polyacrylamide, polymethyl acrylate, polymethyl methacrylate,
polyvinylacetate, polyvinylpyrroidone, polytetraethylene glycol
diacrylate and polyimide.
3. The structure of the electrochemical separation membrane
according to claim 1, wherein the base-phased polymer part becomes
gelatinous when contacts an electrolyte.
4. The structure of the electrochemical separation membrane
according to claim 1, wherein the electrochemical separation
membrane has a total thickness ranging 10.about.60 .mu.m.
5. The structure of the electrochemical separation membrane
according to claim 1, wherein the fabric-supported part is selected
from the group consisting of at least one of polyethylene fibers,
polypropene fibers, polybutene fibers, polypentene fibers, and
polyethylene terephthalate fibers, a diameter of the
fabric-supported part ranges between 0.5.about.30 .mu.m, and a size
of the micro holes ranges between 0.1.about.20 .mu.m.
6. The structure of the electrochemical separation membrane
according to claim 1, wherein the inorganic particles are selected
from the group consisting of at least one of metal oxides, metal
carbides, metal nitrides, metal titanate, and metal phosphate, and
the particle size of the inorganic particles ranges between
0.01.about.30 .mu.m.
7. The structure of the electrochemical separation membrane
according to claim 1, wherein the base-phased polymer part further
includes a plurality of micro holes with size of 0.1.about.5 .mu.m,
and a porosity of the base-phased polymer part is 40.about.75%.
8. A manufacturing method for fabricating an electrochemical
separation membrane, comprising: a polymer slurry preparing step:
preparing a polymer base-phased material solution including a
polymer base-phased material dissolved in solvent and inorganic
particles with 0.1 wt %.about.50 wt % distributed in the polymer
base-phased material solution; a coating step: forming the polymer
base-phased material solution around a porous fabric support part
by dipping or coating, wherein the polymer base-phased material is
filled into the micro holes of the porous fabric support part and
the electrochemical separation membrane is thus formed; and a
drying step: drying the electrochemical separation membrane by
keeping the same standing still, air drying or heating.
9. The manufacturing method for fabricating the electrochemical
separation membrane according to claim 8, wherein the polymer
base-phased material is selected from the group consisting of at
least one of polyvinylidene fluoride, polyethylene terephthalate,
polyurethane, polyethylene oxide, polypropylene oxide,
polyacrylonitrile, polyacrylamide, polymethyl acrylate, polymethyl
methacrylate, polyvinylacetate, polyvinylpyrroidone,
polytetraethylene glycol diacrylate and polyimide.
10. The manufacturing method for fabricating the electrochemical
separation membrane according to claim 8, wherein the porous fabric
support part is selected from the group consisting of at least one
of polyethylene fibers, polypropene fibers, polybutene fibers,
polypentene fibers, and polyethylene terephthalate fibers, a
diameter of the fabric-supported part ranges between 0.5.about.30
.mu.m, and a size of the micro holes ranges between 0.1.about.20
.mu.m.
11. The manufacturing method for fabricating the electrochemical
separation membrane according to claim 8, wherein the inorganic
particles are selected from the group consisting of at least one of
metal oxides, metal carbides, metal nitrides, metal titanate, and
metal phosphate, and a particle size of the inorganic particles
ranges between 0.01.about.30 .mu.m.
12. The manufacturing method for fabricating the electrochemical
separation membrane according to claim 8, wherein the solvent is
selected from the group consisting of at least one of acetone,
butanone, N-methylpyrrolidone, tetrahydrofuran, dimethylformamide,
dimethylacetamide, and tetramethylurea.
13. The manufacturing method for fabricating the electrochemical
separation membrane according to claim 8, wherein the polymer
base-phased material solution further includes an adhesive which is
selected from the group consisting of at least one cellulose
acetate, cellulose acetate butyrate, cellulose acetate propionate,
ethyl cellulose, cyanoethyl cellulose, cyanoehyl polyvinyl alcohol
and carboxymethyl cellulose, and the adhesive has a weight
percentage 0.1.about.20 wt % of the organic particles.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority of Taiwanese patent
application No. 101120929, filed on Jun. 11, 2012, which is
incorporated herewith by reference
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a structure of an
electrochemical separation membrane and a manufacturing method for
fabricating the sane, more particularly to an electrochemical
separation which is used in a lithium ion battery for improving the
shrinkage and enhances the safety of the batteries under high
temperature.
[0004] 2. The Prior Arts
[0005] The traditional secondary batteries, such as nickel-cadmium
batteries and nickel-hydride batteries, have been replaced by
secondary lithium ion batteries since the secondary lithium ion
batteries were presented to the public due to the advantages of
high energy density and long circle of lifespan. Since Sony Company
commoditized the secondary lithium ion batteries in 1991, the
share-of-market of the secondary lithium ion battery is increased
continuously, and the global output value of the secondary lithium
ion battery surpasses the total sum of the nickel-cadmium batteries
and the nickel-hydride batteries in a decade. Based on technology
of the battery design and improvement materials in existence and
the development of new materials, the application fields of the
secondary lithium ion batteries are broadened. Hence, the secondary
lithium ion batteries become the first choice in 3C products
recently due to its advantages of the lighter, shorter and thinner
designs.
[0006] In the markets of consumer electronics and electric
vehicles, the most important evaluating item is safety. Therefore,
raising the safety of the safety-related materials such as the
separation membrane is the key work in battery design. The function
of the separation membrane is to separate the electrons and to make
the ions pass through freely, and to avoid occurrence of the short
circuit between the anode and the cathode. In addition, the
separation membrane of the secondary lithium ion battery is
required to shutdown the micro holes which function as
ions-passages when the temperature of battery raises abnormally to
avoid the thermal escape, burning and further explosion due to the
continuously rising of the temperature. Therefore, the strength,
thickness, distribution of micro holes and thermal actuating of the
separation membrane, as the quality indexes, determine the factors
of the capacitance of battery, circle lifetime of battery and
safety, and also influence the marketing development. Moreover, the
price of the separation membrane is only 20% of the cost of the
secondary lithium ion battery, such that the development of the
separation membrane plays an important factor in the field.
[0007] Recently, most of the secondary lithium ion batteries use
porous polyolefin polymers as the separation membrane, wherein the
polyolefin polymers include polypropylene (PP), polyethylene (PE)
and PP/PE/PP layer-laminated. The polyolefin polymers have the
advantages of low-cost, good mechanical strength and high chemical
stability.
[0008] Manufacturing methods for fabricating the separation
membrane are divided into a dry type method and a wet type method.
The processes of dry type method are disclosed in U.S. Pat. Nos.
5,952,120, 6,207,053 and 6,368,742. Those methods use polyolefin
polymers, i.e. PE, PP and PP/PE/PP layer-laminated, as the main
materials for manufacturing the separation membrane. Firstly,
extruding the melting materials into a membrane and then stretching
out in single direction or bi-directionally. In the stretching
process, the lamella structure of hard elastic materials, which is
arranged in parallel and perpendicular to the extruding direction
are stretched to form micro holes. Finally, those micro holes are
fixed by a thermal boarding process. The cost of the dry type
method is low, but the ultimate price of the separation membrane is
still high because the conditions of processes are strict to meet
the specification of the secondary lithium ion battery. The shape
of micro holes manufactured by the dry type method is straight, and
short circuit may occur in the cathode end of the secondary lithium
ion battery because the separation membrane is pierced by the
lithium crystal. In order to solve the safety problem,
manufacturing a thermal resistance layer or adding inorganic
particles are generally used.
[0009] For the lithium ion battery system, since the polarity of
the polyolefin polymers is very low, and the electrolyte of the
lithium ion battery is an organic solution with high dielectric
coefficient and high polarity in which lithium salts are dissolved,
such that the affinity between the polyolefin polymers and
electrolyte is not good, so that it causes the bad wetting effect
of electrolytes to the separation membrane, and the ion electric
conductivity of whole lithium ion battery is lower than the ion
electric conductivity of the electrolytes. In order to improve the
affinity between the polyolefin polymers and electrolyte and raise
the wetting effect, some researches modify the surface properties
of the polyolefin polymers, for example, U.S. Pat. No. 6,322,923
disclosed that a gelatinous polymer is covered on the polyolefin
porous membrane to enhance the wetting effect. On the other hand,
some methods change the material of the separation membrane with
materials having high-affinity to the electrolyte, and it further
raises the affinity to the anode and cathode boards.
[0010] As described above, the micro holes of the separation
membrane should be shutdown to stop the ion conduction and further
cut off the current when the batteries is overheated due to the
exothermal reaction or is subjected thermal breaking due to
external high intensive heat. When the material reaches the melting
point, i.e., the melting point of polyethylene is 120.degree. C.,
the state of the separation membrane changes from solid state to
liquid state, and the mechanism of shutdown starts. However, in
order to prevent the anode from contacting the cathode directly in
the melting state, the integrity of the separation membrane should
be maintained before melting. As the internal temperature of the
battery increases continuously, the separation membrane will
meltdown finally, and causes short circuit due to contact of anode
and cathode, and the battery may explode. The temperature
difference between shutdown and meltdown is so-called safe
threshold, and the temperature difference of traditional or general
polyolefin separation membrane is relatively small, for example,
30.degree. C. to 50.degree. C., and based on molecular mass of the
materials. Recently, the manufacturers of the separation membrane
realize the disadvantages of traditional separation membrane (the
main material is PE), and are searching to improve the safety in
some ways. Hence, inorganic composite separation membrane will play
a key role within the technologies in manufacturing separation
membrane of high power capacitance batteries in the near
future.
[0011] Nowadays, a single-layered PE separation membrane is used in
most of the inorganic composite separation membranes as a base
material composition of the inorganic composite separation
membrane. The purposes of using the single-layered PE separation
membrane are to maintain the thickness of the inorganic composite
separation membrane, and also to maintain the mechanical strength
and high thermal resistance. The inorganic composite separation
membrane mainly includes polyamide, nano-meter
oxide(Al.sub.2O.sub.3 and SiO.sub.2), a base material and a ceramic
composite layer, wherein the base material of the inorganic
composite separation membrane is a single-layered porous PE thin
film (14.about.16 .mu.m), the ceramic composite layer (4 .mu.m) is
used to enhance the mechanical strength and the uniformity of
thermal conductivity of the single-layered porous PE thin film, and
the total thickness of the inorganic composite separation membrane
is 18.about.20 .mu.m. In addition, the porosity of ceramic
composite layer (60.about.65%) is higher than the porosity of the
single-layered porous PE thin film (30.about.35%), such that the
ceramic composite layer has no influence regarding the wetting
effect of the separation membrane and the permeation of the lithium
ions.
[0012] U.S. Pat. No. 7,959,011 disclosed a separation membrane made
of a PET non-woven fabric mixed with Al.sub.2O.sub.3, ZrO.sub.4 and
SiO.sub.2. Since an inorganic layer is formed between the metal
oxide and PET after continuous dipping, drying and sintering, such
that the separation membrane has higher thermal stability and
deform resistance under heating, and does not shrink and melt under
200.degree. C. Therefore, the safety of the power batteries is
improved. However, the cohesive strength between the composite
layer and base material membrane is not sufficiently enough, and
the stability of separation membrane is neither enough.
[0013] Chinese patent publication No. 101481855A disclosed a
manufacturing method of SiO.sub.2/polyvinylidene nano-composite
fabric membrane. This method applies sol-gel principle to change
the properties of the nano SiO.sub.2 particles, co-mixes the nano
SiO.sub.2 particle and the polyvinylidene, and finally manufactures
the nano-composite fabric membrane with the electrospinning
technology. Chinese patent publication No. 101826606A disclosed a
polytetrafluoroethene lithium ion battery separation membrane and
manufacturing method thereof. In this method, a
polytetrafluoroethene porous membrane is used as a base material,
then a polymer is formed on one or two surfaces of the base
material by dipping, coating or sprays coating, and finally a
composite membrane is obtained after drying and thermal-pressing
shaping. The lifespan and safety (the shutdown temperature is about
100.about.150.degree. C.) of the battery separation membrane is
improved based on its chemical stability, thermal stability and
antioxidative activity.
[0014] US patent publication No. 2010/0,316,903 A1 also describes a
method for manufacturing composite separation membrane. In this
method, firstly coating a slurry consist of adhesive and ceramic
particles on a surface of a porous base material, wherein the
adhesive is a cross-linking polymer, such that the adhesive and the
porous base material cross-links after slurry coating, and the
adhesion strength between the adhesive and the base material is
enhanced. US patent publication No. 2012/0,015,254 A1 disclosed
enhancing the adhesion strength by another method, the method coats
slurry comprising adhesive and ceramic particles with dielectric
coefficient higher than 5 on a porous base material firstly, and
then coating a polymer solution on the outside by the
electrochemical method to form a second coating layer for covering
the base material and enhancing the stability of the separation
membrane. However, the second cross-linking or the second coating
makes the processes more complicated.
[0015] Summarizing the description above, in order to prevent the
separation membrane of the high power lithium ion battery from
deforming or twisting under high temperature and thus influencing
the safety of lithium ion battery, the mechanical strength and
thermal stability should be improved to enhance the safety of the
lithium ion battery; and most of the prior arts coat slurry with
ceramic particles on the two sides of the base membrane to form
protection layers, however, the thickness and the accuracy of the
protection layers are difficult to control and the adhesive
strength is not sufficiently enough, and it could influence the
performance of the separation membrane.
SUMMARY OF THE INVENTION
[0016] A main objective of the present invention is to provide a
structure of electrochemical separation membrane including a
base-phased polymer part, a fabric-supported part and inorganic
particles, wherein the fabric-supported part is striped-shape and
distributed in the base-phased polymer part to provide the mechanic
strength for supporting the base-phased polymer part, and the
inorganic particles are uniformly distributed in the base-phased
polymer part with 0.1 wt %.about.50 wt %, and the base-phased
polymer part is formed around the fabric-supported part in a
continuous phase structure and has porous structure. The total
thickness of the electrochemical separation membrane 1 ranges
between 10.about.60 .mu.m.
[0017] The fabric-supported part is selected from the group
consisting of at least one of polyolefine fibers, and has a porous
structure with micro holes, such that the base-phased polymer part
can fill into those micro holes and combine with the
fabric-supported part tightly. The inorganic particles are selected
from the group consisting of at least one of metal oxides, metal
carbides, metal nitrides, metal titanate, and metal phosphate, and
the particle size ranges between 0.01.about.30 .mu.m. The inorganic
particles have high burning temperature, and high decomposition
temperature to prevent the temperature from over-rising, and
provide support strength for the base-phased polymer part to
prevent the electrochemical separation membrane from over
shrinking.
[0018] The other objective of the present invention is to provide a
manufacturing method for fabricating an electrochemical separation
membrane including polymer slurry preparing step, a coating step,
and a drying step. The polymer slurry preparing step is to prepare
a polymer base-phased material solution comprising a polymer
base-phased material, solvent and inorganic particles, wherein the
polymer base-phased material is dissolved in the solvent and the
inorganic parties are distributed in the polymer base-phased
material solution with 0.1 wt %.about.50 wt %. In addition, the
polymer base-phased material solution further includes an
adhesive.
[0019] The coating step is to form the polymer base-phased material
solution around a porous fabric support part by dipping or coating
such that the polymer base-phased material can fill into the micro
holes of the porous fabric support part and an electrochemical
separation membrane is thus formed. The drying step is to dry the
polymer base-phased material solution by standing still, air drying
or heating such that the electrochemical separation membrane with
the base-phased polymer part, the fabric-supported part and the
inorganic particles is thus formed.
[0020] The technical features in the structure and a manufacturing
method for fabricating the electrochemical separation membrane of
present invention are that the polymer base material solution fill
into the micro holes of the fabric-supported part to provide the
mechanic strength in the structure of the electrochemical
separation membrane of the present invention such that the adhesive
strength is improved. Moreover, the inorganic particles reduce the
shrinking of separation membrane and improve the thermal stability
under the high temperature. Further, the lithium ion battery
applying the electrochemical separation membrane of present
invention has reduced total resistance, increased charge/discharge
capacitance and longer lifespan.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The present invention will be apparent to those skilled in
the art by reading the following detailed description of a
preferred embodiment thereof, with reference to the attached
drawings, in which:
[0022] FIG. 1 is a top view conceptual diagram of the
microstructure of the electrochemical separation membrane of the
present invention.
[0023] FIG. 2 is a partial enlarged drawing of base-phased polymer
part in FIG. 1.
[0024] FIG. 3 is a flow chart of the manufacturing method for
fabricating an electrochemical separation membrane of the present
invention.
[0025] FIGS. 4A to 4C are diagrams showing the charge/discharge
testing and lifetime analysis of the lithium ion battery used the
electrochemical separation membrane of Experiment Example 1
comparing with the lithium ion battery used commercial Celgard 2320
separation membrane.
[0026] FIG. 4D is a diagram showing the relationship of current
density and capacitance of the battery used the electrochemical
separation membrane of Experiment Example 1.
[0027] FIG. 5 is a diagram showing the results of charge/discharge
properties of the battery used the electrochemical separation
membrane of Experiment Example 2 by rates of 1 C and 3 C.
[0028] FIGS. 6A to 6B are diagrams showing the charge/discharge
testing by rates of 0.2 C and 3 C and thermal performance at
55.degree. C. of the lithium ion battery using the electrochemical
separation membrane of Experiment Example 4 comparing with the
lithium ion batteries used commercial Celgard 2320, 2400 separation
membranes.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] The accompanying drawings are provided for further
understanding of the invention, and are incorporated in and
constitute a part of this specification. The drawings illustrating
the embodiments of the invention together with the description,
serve to explain the principles of the present invention.
[0030] Please refer to FIG. 1, which is a top view conceptual
diagram of the microstructure of the electrochemical separation
membrane of the present invention. As shown in FIG. 1, the
structure of the electrochemical separation membrane 1 of the
present invention includes a base-phased polymer part 10, a
fabric-supported part 20 and inorganic particles 30, wherein the
fabric-supported part 20 is striped-shape and is distributed in the
base-phased polymer part 10 to provide the mechanic strength for
supporting the base-phased polymer part 10. The inorganic particles
30 are uniformly distributed in the base-phased polymer part 10
with 0.1 wt %.about.50 wt %. The base-phased polymer part 10 is
formed around the fabric-supported part 20 in continuous phase
structure and is porous structure. The total thickness of the
electrochemical separation membrane 1 ranges between 10.about.60
.mu.m.
[0031] The base-phased polymer part 10 is selected from the group
consisting of at least one of polyvinylidene fluoride, polyethylene
terephthalate, polyurethane, polyethylene oxide, polypropylene
oxide, polyacrylonitrile, polyacrylamide, polymethyl acrylate,
polymethyl methacrylate, polyvinylacetate, polyvinylpyrroidone,
polytetraethylene glycol diacrylate and polyimide, and becomes
gelatinous when the base-phased polymer part 10 contacts with the
electrolyte.
[0032] The fabric-supported part 20 is selected from the group
consisting of at least one of polyethylene fibers, polypropene
fibers, polybutene fibers, polypentene fibers, and polyethylene
terephthalate fibers, and the diameter of the fabric-supported part
20 ranges between 0.5.about.30 .mu.m. The fabric-supported part 20
is a porous structure and has micro holes with diameter ranging
0.1.about.20 .mu.m, such that the base-phased polymer part 10 can
fill into those micro holes and combined with the fabric-supported
part 20 tightly.
[0033] The inorganic particles 30 are selected from the group
consisting of at least one of metal oxides, metal carbides, metal
nitrides, metal titanate, and metal phosphate, and the particle
size is in the range of 0.01.about.30 .mu.m, wherein
Al.sub.2O.sub.3, SiO.sub.2, TiO.sub.2, CaCu.sub.3Ti.sub.4O.sub.12,
Li.sub.4Ti.sub.5O.sub.12, CaCO.sub.3, ZrO.sub.4, CaO, LiFePO.sub.4
are preferred. The inorganic particles 30 has high burning
temperature, and high decomposition temperature to prevent the
temperature from over rising, and provides support strength to the
base-phased polymer part 10 to prevent the electrochemical
separation membrane 1 from over shrinking.
[0034] Please refer to FIG. 2, which is a partial enlarged drawing
of base-phased polymer part in FIG. 1. As shown in FIG. 2, not only
the inorganic particles 30 are comprised in the base-phased polymer
part 10, but also a plurality of micro holes are distributed
uniformly, wherein the diameter of those micro holes ranges between
0.1.about.5 .mu.m, and the porosity of the base-phased polymer part
10 ranges between 40.about.75%.
[0035] Please refer to FIG. 3, which is a flow chart of the
manufacturing method for fabricating an electrochemical separation
membrane of the present invention. As shown in FIG. 3, the
manufacturing method S1 of an electrochemical separation membrane
of the present invention includes a polymer slurry preparing step
S10, a coating step S20, and a drying step S30. The polymer slurry
preparing step S10 is to prepare a polymer base-phased material
solution including a polymer base-phased material, solvent and
inorganic particles, wherein the polymer base-phased material is
dissolved in the solvent and the inorganic parties are distributed
in the polymer base-phased material solution with 0.1 wt %.about.50
wt %. In addition, the polymer base-phased material solution
further includes an adhesive. The base-phased polymer part is
selected from the group consisting of at least one of
polyvinylidene fluoride, polyethylene terephthalate, polyurethane,
polyethylene oxide, polypropylene oxide, polyacrylonitrile,
polyacrylamide, polymethyl acrylate, polymethyl methacrylate,
polyvinylacetate, polyvinylpyrroidone, polytetraethylene glycol
diacrylate and polyimide. The solvent is selected from the group
consisting of at least one of acetone, butanone,
N-methylpyrrolidone, tetrahydrofuran, dimethylformamide,
dimethylacetamide, and tetramethylurea.
[0036] The adhesive can be selected from the group consisting of at
least one of cellulose acetate, cellulose acetate butyrate,
cellulose acetate propionate, ethyl cellulose, cyanoethyl
cellulose, cyanoehyl polyvinyl alcohol and carboxymethyl cellulose,
and has a weight percentage 0.1.about.20 wt % to the organic
particles.
[0037] The coating step S20 to form the polymer base-phased
material solution around a porous fabric support part by dipping or
coating; such that the polymer base-phased material can fill into
the micro holes of the porous fabric support part and an
electrochemical separation membrane is formed.
[0038] The drying step S30 is to make the solvent vaporize from the
polymer base-phased material solution by standing, air drying or
heating; such that the polymer base-phased material is dried and
the electrochemical separation membrane 1 with the base-phased
polymer part 10, the fabric-supported part 20 and the inorganic
particles 30 as shown in FIG. 1 is formed.
[0039] The following four experimental examples are conducted to
describe the structure and manufacturing of the electrochemical
separation membrane and those experimental examples are only used
to describe the preferred embodiments, but not to limit.
EXPERIMENTAL EXAMPLE 1
[0040] In Experimental Example 1, dissolving the polyvinylidene
fluoride into acetone and adds SiO.sub.2 particles (particle size
are about 5 nm) of 0.7 wt %, and then stirrings 16 hours or more to
form slurry as the polymer base-phased material solution. Then,
coating the polymer base-phased material solution on polypropene
fibers by dip coating.
[0041] Combine the dried electrochemical separation membrane made
from Experimental Example 1 with LiFePO.sub.4 to form the anode
material, lithium foil to form the cathode material, and LiPF.sub.6
to form the electrolyte as a button cell by the traditional
combining technology, and then compares the fast charge/discharge
property and the lifespan with the button cell with commercial
Celgard 2320 separation membrane. The result is shown as FIGS. 4A
to 4C, it shows that the performance of the electrochemical
separation membrane made of Experimental Example 1, is similar to
the commercial separation membrane under different discharge rate,
and the impedance is also similar to the commercial separation
membrane, in addition, the lifespan of the device is further
increased. Therefore, the electrochemical separation membrane, made
from Experimental Example 1, is used as the separation membrane of
an electrochemical device.
[0042] Combine the dried electrochemical separation membrane made
of Experimental Example 1, active carbon to form the anode and
cathode material, and LiPF.sub.6 to form the electrolyte as a
button super capacitance by the traditional combining technology,
and then test the charge/discharge properties under different
current density. The relationship of capacitance and
electrochemical current density of the button super capacitance
with the electrochemical separation membrane, made from
Experimental Example 1, is shown as FIG. 4D; the results show that
the electrochemical separation membrane, made from Experimental
Example 1, is applied in the button super capacitance.
[0043] In addition, test the thermal shrink property of the
electrochemical separation membrane, made from Experimental Example
1, under high temperature and compare with the commercial Celgard
2320 separation membrane. The test method is that fix two ends of
the separation membrane on a glass carrier, then heat 2 hours in
the heater with a constant temperature 130.degree. C. After this
test, the commercial Celgard 2320 separation membrane shrinks over
20%, but the electrochemical separation membrane, made from
Experimental Example 1, only shrinks 1% or less. Therefore, we can
understand that filling polymer of the continuous phase structure
and adding the inorganic reduce the thermal shrinking at high
temperature, and improve the safety at high temperature.
EXPERIMENTAL EXAMPLE 2
[0044] Experimental Example 2 uses an explanted and high density
fabric material as the fabric-supported part; such that the
gelatinous polymer base material solution can fill into micro holes
of the porous fabric material to form the electrochemical
separation membrane. The manufacturing method of Experimental
Example 2 is similar to the Experimental Example 1, and
Experimental Example 2 uses the polyvinylidene/acetone solution and
adds SiO.sub.2 particles of 1.5 wt %, and then stirs 8 hours or
more to form slurry as the polymer base-phased material solution.
Then, coat the polymer base-phased material solution on the
explanted polypropene fibers by dip coating.
[0045] Combine the dried electrochemical separation membrane, made
from Experimental Example 2, with LiFePO.sub.4 to form the anode
material, lithium foil to form the cathode material, and LiPF.sub.6
to form the electrolyte as a button cell by the traditional
combining technology, and then test the charge/discharge properties
by rates of 1 C and 3 C, the results are shown in FIG. 5.
EXPERIMENTAL EXAMPLE 3
[0046] Experimental Example 3 uses the polyvinylidene/acetone
solution described above and adds CaCu.sub.3Ti.sub.4O.sub.12 (CCTO)
particles of 1.5 wt %, and then stirs uniformly to form slurry as
the polymer base-phased material solution, wherein the crystal
structure CaCu.sub.3Ti.sub.4O.sub.12 is the pervoskite cubic
structure, which has keep a huge dielectric coefficient in a
temperature range. Meanwhile, the ethyl cellulose is added into the
slurry as adhesive, then stirs for 4 hours or more, and coat the
polymer base-phased material solution on the polypropene fibers by
dip coating. After fully drying in the room temperature, the
electrochemical separation membrane with thickness 30-40 .mu.m is
thus obtained, in which a porous fabric material is used a support
part, and a continuous phase structure of
polyvinylidene/CaCu.sub.3Ti.sub.4O.sub.12 fill into the micro holes
of the porous fabric material.
EXPERIMENTAL EXAMPLE 4
[0047] Experimental Example 4 uses a high density polyethylene
membrane as a support part, and coat the polyvinylidene
fluoride/acetone solution with 0.7 wt % SiO.sub.2 particles on the
high density polyethylene membrane by dip coating to form a
electrochemical separation membrane.
[0048] Combine the dried electrochemical separation membrane, made
from Experimental Example 4, with LiFePO.sub.4 to form the anode
material, lithium foil to form the cathode material, and LiPF.sub.6
to form the electrolyte as a button cell by the traditional
combining technology, and then test charge/discharge properties by
rates of 0.2 C and 3 C and high temperature performance, and
compare with commercial Celgard 2320 and 2400 separation membranes,
the results are shown as FIGS. 6A and 6B. The results show that the
electrochemical separation membrane, made from Experimental Example
4, has better stability and performance under high temperature.
[0049] The technical features in the structure and a manufacturing
method for fabricating an electrochemical separation membrane of
present invention are that the polymer base material solution are
filled into the micro holes of the fabric-supported part providing
the mechanic strength in the structure of the electrochemical
separation membrane of the present invention, such that the
adhesive strength is improved. Moreover, the inorganic particles
reduce the shrinking of separation membrane and improve the thermal
stability under the high temperature. Further, the lithium ion
battery applying the electrochemical separation membrane of present
invention possesses reduced total resistance, increased
charge/discharge capacitance and longer lifespan.
[0050] Although the present invention has been described with
reference to the preferred embodiments thereof, it is apparent to
those skilled in the art that a variety of modifications and
changes may be made without departing from the scope of the present
invention which is intended to be defined by the appended
claims.
* * * * *